Circuit breaker



Nav. s, 1938. v WBER 2,135,864

C IRCUIT BREAKER Filed Sept. 25, 1936 Patented Nov. 8, 1938 UNITED STATES' CIBEUIT BREAKER vicm- Weber. si. Louis, Mo., signori to 'rin Emerson Electric Mig. Co., St. Louis, Mo., a

corporation of Missouri Application September 23, 1936., Serial No. 102,093

16 Claims.

'I'he present invention relates generally to circuit breakers, and more particularly to a thermally actuable circuit breaker which includes automatic reset mechanism and snap make-andbreak action. y

An object of the present invention is to provide a thermally-actuatable circuit breaker which is adapted to interrupt the electrical circuit of an energy-translating device upon an excessive current therethrough or upon a dangerous internal overheating of the device.

Another object is to provide a thermallyactuatable circuit breaker which includes means for automatically resetting the device subsequent to a current interruption action thereof.

Another object is to provide a thermallyactuatable circuit breaker which includes a heating element adapted to actuate the circuit breaker by current passing therethrough.

Another lobject is to provide a thermallyactuatable circuit breaker which includes overcenter snap mechanism for closing and opening the contacts thereof to prevent arcing.

Another object is to provide a thermallyactuatable circuit breaker which is adapted to eiciently and effectively protect an energy-translating device, as a motor, under a variety of conditions.

Another object is to provide a thermallyactuatable circuit breaker which is compact in structure, cheap to manufacture and adapted to fulfill all of the purposes and advantages sought therefor.

Other objects and advantages will be apparent tion with the accompanying drawing, in which Fig. 1 is a plan view of a thermally-actuatable circuit breaker constructed in line with the present invention.

Fig. 2 is a side elevation of the device shown in Fig. 1.

Fig. 3 is a section on the line 3--3 of Fig. 1, showing the elements in positions whereby the contacts are closed.

Fig. 4 is likewise a section on the line 3-3 of Fig. l, showing the elements in positions whereby the contacts are open.

Fig. 5 is a section on the line 5-5 of Fig. 2.

Fig. 6 is a section on the line 6-6 of Fig. 4.

Fig. 'I is a plan view of preferred embodiments of a pivot plate and an upper switch blade in assembled relation.

Fig. 8 is a plan view of a preferred embodiment of a lower switch blade and a supporting plate therefor in assembled relation.

from the following description, taken in conjunc- (Cl. 20G-113) Fig. 9 is a plan view of preferred embodiments of a U-shaped bracket support.

Fig. 10 is a perspective of a preferred embodiment of a connecting plate.

Referring more particularly to the drawing by reference numerals, II represents a base preferably of a configuration shown in Fig. 1 which is adapted to support in operative relation the elements of the instant thermally-actuatable circuit breaker. A support, generally indicated I2, of U-shaped transverse cross-section rests on the base II and is connected thereto by nut and bolt means I3 extending through a horizontal flange I4 on the one side and by an extension I5 of the vertical leg I1 extending into an opening I6 in the base II on the other side. The support I2 further includes a horizontal bight I9 and a second leg I6. A bimetallic element 20 of generally elongated rectangular configuration is connected at one end by bolt and nut means 2|, or the like, to the bight I9 of the support I2. The bimetallic member 2li has a major notch 22 and opposed minor notches 23 in the free end for a purpose to be described.

A. U-shaped bracket, generally indicated 25, rests on the base II beneath that end of the bimetallic member 20 which contains the notches 22 and 23, and is connected to the base by a brad 26 which extends through centrally disposed hole 21 in the bracket and a hole 28 in the base. Pivotal movement of the bracket about the brad 26 is prevented by a downwardly directed extension 29 of the bracket which nests in a hole 30 in the base. The bracket 25 includes a bight 3| which rests against the upper surface of the base II, vertically disposed legs 32 having opposed openings 33 therein, and generally upwardly directed opposed prongs 34 and 35.

A flat pivot plate 36 has trunnions 31 which are adapted to extend into the holes 33 of the bracket 25 to pivotally support the plate. The plate is cut out at 38 and is grooved at 39 and 40 along its transverse edges 4I and 42, respectively. An upper switch blade 44 of generally elongated rectangular configuration includes an outer peripheral portion 45 and an interiorly located tongue 46. 'I'he tongue 46 is spaced from the peripheral portion 45 by longitudinal slots 41 and a cut away portion 48. The peripheral portion 45 includes an interior transverse edge 49 which is adapted to fit within the groove 39. The tongue 46 terminates in a transversevedge 50 which is opposed to the edge A4!) and is adapted to t within the groove 40. The distance between the edge 49 and the edge 50 is predeterminately less than the distance between the apexes of the grooves 39 and 40 so that the tongue assumes, when in assembled position upon the flat plate 36, the bowed position shown in Fig. 2, the operative purpose of which will be subsequently described. At the end of the blade 44 remote from its` connection with the plate 35, there is a contact 5|. A flange or apron 52 extends at right angles to and along each longitudinal side of the peripheral portion 45 to render that portion substantially rigid.

A connecting plate 53 of rectangular shape, as is shown in Fig. 10, had two sets .of opposed notches 54 and 55, respectively. The notches 54 engage the notch 22 of the bimetallic member 25, and the notches 55 engage the pivotal plate 35 through the cut out 38, as will be apparent from an inspection of Fig. 6. The connecting plate 53 is held in position by means of a strap 55, which is connected tothe bimetallic member 25 and engages in the notches 23.

A lower switch blade support 55 rests on the base I beneath the bimetallic member 25 and the upper blade 44 and is connected thereto by brads 59, or the like, intermediate the bracket 25 and the support i2. The support 55 is generally rectangular in shape and includes the connecting portion and the raised portion 5|, and is cut away centrally to provide an opening 52. A lower switch blade 64 is connected to the support 55 by the aforementioned securing means 59 and extends through the opening 52 and beneath the raised portion 6 I, as can be seen from Figs. 4 and 8. A contact 65 is fixed to the free end ot the blade 64.

A sinuous heater element 61 is connected to the base at terminals 55 and 65. The heater element is disposed to lie beneath or above the bimetallic element or member 25, the illustration at Figs. l and 2 showing it beneath. Leads 15 and 1| for the heater element 51 are connected to the terminals 68 and 59, respectively. A lead 12 is connected to the brad 26 which thereby serves as a terminal, and a lead 13 is connected to one of the brads 55 which likewise thereby serves as a terminal.

Operation The instant thermally-actuatable circuit breaker is adapted to be used with energy-translating devices generally, but it is particularly useful in conjunction with a motor. In practice, the circuit breaker is disposed within a casing of a motor in a position to receive the i'ull effect of ambient heat. The bimetallic member 20 is adapted to iiex outwardly from the base |I through a predetermined temperature range reached either from heat within the motor casing, as that which accumulates from a continuous overload of the motor, or from a short circuit in the line, or a stoppage of the armature, in which case a large current would be passed through the windings and a proportionate amount through the heater element 51.

It is thus apparent that the prsent invention is constructed to protect a motor under varied operating conditions. 'I'he mechanical functioning of the circuit breaker is distinctly novel and includes an over-center snap-action. As has been described, the bimetallic member 20 is connected in a positive manner to the pivot plate 36 by means of the connecting plate 53. Hence, when the free end of the bimetallic member 25 moves away from the base I l, the plate 35 will be pivoted about its trunnion support 31, the groove 39 and its associated blade edge 43 likewise moving away from the base and the groove 45 and its associated tongue edge 50 moving toward the base in this pivotal action. The switch blade 44 is connected to the plate 35 in an over-center relation, the blade 44 pivoting along the edge 43 within the groove 33 and being biased to the one side or the other of center position by means oi the edge 55 of the bowed tongue 45 acting within the groove 45. The pivotal movement o! the plate 35 is limited clockwise by the stop 35 and counterclockwise by the stop 34.

Referring to Fig. 3, the elements are shown in positions wherein the contacts 5| and 55 are in closed position. That point established by the apex of the groove 45 is above a line between the point established by the apex of the groove 35 and the point of connection oi the contact 5| to the end of the blade 45. The bowed tongue 45 biases the plate 35 toward counterclockwise pivotal action and hence forces the contact 5| into engagement with the contact `55 in clockwise pivotal movement of the blade 44 about the edge 45.

Upon sufficient amount of heat being supplied to the bimetallic member 25, the free end moves outwardly, as has been stated, from the base thereby pivoting the plate 35 clockwise about its trunnions 31 until it encounters the stop 35, which prevents further movement. In this movement. that aforesaid point established by the apex or the groove 40 moves across the line extending between that point established by the groove 33 and that point established by the connection ot the Contact 5| to the end of the blade 44. On passing this line, the direction of the force applied by the bowed tongue 45 changes, and the bias against the plate 35 becomes clockwise. Hence, the contact 5| will be snapped away from the contact 55 and up against the bolts 2| as stops. The snapping open of the contacts 5| and 55, of course, interrupts the electrical circuit oi the motor, thereby stopping the same. As the temperature oi' the air surrounding the bimetallic member 20 drops, the free end oi' the member returns to its normal position, thereby pivoting the plate 35 in a counterclockwise direction until it encounters the stop 34, which carries the tongue edge 50 upwardly across center to snap the contact 5| into closed relation with the contact 55. The circuit breaker is thus automatic in its operations of opening and closing. It is apparent that the heater element 51 may be associated in any desired manner with the circuit breaker.

It is clear that a thermally-actuated circuit breaker has been provided which achieves all oi' the advantages and purposes sought. It is to be understood that the above description and the accompanying drawing have been given by way of example, and not by way of limitation, the invention being limited only by the following claims.

What I claim is:

1. A circuit breaker comprising a pivoted member, an element pivoted to said member and carrying a contact at a free end, said pivotal connection between said member and said element including two spaced cooperating groove and edge connections, a second contact disposed to cooperate with said first contact, and means to eiect snap pivotal movement of said element including a thermally-actuated member.

2. A circuit breaker comprising a base, a support thereon, a bimetallic member fixed to the support and extending over the base, a bracket on the base, a plate pivoted to the bracket, a

' switch blade pivoted to and supported by the plate and carrying a Contact, a second contact, and a connection between the bimetallic member and the plate to that side of the plate pivot just remote from the contacts.

3. A circuit breaker comprising a base, a bimetallic member supported thereon, a member pivotably supported on the base, an element supported by said member yfor pivotal movement relative thereto and carrying a contact, a second contact, and a connection between said bimetallic member and Asaid pivoted member, whereby movement of said bimetallic member will effect pivotal movements of the pivoted mem.. ber and the element in opposite directions to break or make the contacts.

4. A circuit breaker comprising a base, a bracket thereon, a plate pivoted on the bracket, a resilient switch blade supported by the plate by supporting means including two groove and edge connections whereby the switch blade is biased out of the plane oi the plate to one side or the other, means defining the limits of movement of the free end of the blade, a contact on the blade, a second contact, and means to move said blade alternately into its biased positions to snap make and break said contacts.

5. A circuit breaker comprising a base, a bracket supported thereon, a plate pivoted to the bracket, a switch blade pivoted to and supported by the plate and carrying at its free end a contact, a second contact disposed to cooperate .with the first contact, a thermally-actuatable member supported by the base, and a connecting plate between the said member and the plate, so that thermally induced movement of the said member is transmitted to the plate to effect breaking and making of the contacts.

6. A circuit breaker comprising a base, a bracket thereon including opposed upstanding legs, a plate pivoted to the legs, said plate having grooves in its edges parallel to the pivot axis, a switch blade including a cut away portion and an interiorly disposed resilient tongue, the distance between the end of the tongue and an opposed interior edge being less than the distance between the said grooves, said blade being pivotally supported by the said plate by means of the said interior edge and the edge of the tongue resting within the said grooves, a contact on the blade remote from the pivotal support, a second Contact, means limiting the movement of the free end of the blade, and thermallyactuated means to pivot the blade through pivotal movement of the plate to break-and-make the contacts.

7. In a device oi the kind described, a switch blade comprising an elongated element having an interior portion adjacent one end cut away and having a tongue formed irom the remaining interior portion, and a contact at that end of the element remote from the cut away portion.

8. A circuit breaker comprising a base, a'

bracket supported thereon, a plate pivoted to said bracket, said plate including a central cut away portion, a resilient switch blade pivoted to.

said plate and carrying a contact, a second contact, and means to eiiect pivotal movement of the plate to make and break the contacts including a thermally-actuatable member and a connection between the said thermally-actuatable member and the plate including a plate element having two pairs of opposed notches along parallel sides, one of said pair of notches being adapted to cooperate with notches in the said thermally-actuatable member and the other pair with the said cut away portion of the said plate.

9. A circuit breaker comprising a base, a bracket supported thereon, a plate pivoted to the bracket, means to limit the pivotal movement of the plate, an element pivoted to the plate in a manner to effect over-center snap movement of the free end of the element, means to limit the movement of the free end of the element, a contact carried by the free end of said element, a second contact, and means for effecting pivotal movement of the plate and through the plate the element to' make and break the contacts including a thermally-actuatable member.

10. A circuit breaker comprising a support, a member pivoted thereon, a resilient element pivoted to said member, said last pivotal connection including grooves in opposed edges of the member and interior edges of the element, one of said edges being defined by an interior tongue integral with the element and said edges lying closer together unassembled than said grooves, so that in assembled relation said tongue is sprung to bias the element about its other interior edge as a pivot to either side of a center position in snap movement, means limiting the movement' of the free end of the element, a contact on the free end of the element, a second cooperating contact, and means to eiiect said snap movement to make and break the contacts without arcing.

11. A circuit breaker as defined in claim 10, said last named means including a thermallyactuated member.

l2. A circuit breaker comprising a base, a support thereon, a bimetallic thermally-actuatable member connected at one end to the support and extending along and spaced from the base, a U- bracket on the base beneath the free end of the member, a plate pivoted in the legs of the bracket, a resilient upper switch blade connected to the plate for movement thereby, means to limit pivotal movement of the pivoted plate, a plate member connecting the thermally-actuatable member to the pivoted plate so that movement of the former pivots the latter, a resilient upwardly biased lower switch blade disposed beneath the upper switch blade, means to limit the upward movement of the lower blade, and cooperating contacts on the blades, said upper blade being so connected to the pivoted plate that thermally induced movement of the thermally-actuatable member away from the base effects a snap breaking of the contacts and. return movement towards the base a snap making of the contacts, thereby eliminating arcing or" the contacts. v

13. A circuit breaker including a base, a bracket liked to the base, a bimetallic member xed at one end to the bracket and extending along the base, a plate pivotally mounted on the base and disposed therebetween and the said member, a contact carrying blade pivotally supported by said plate, a second contact on the base cooperative with the Contact on the blade, the pivotal connection between the blade and the plate being maintained through 'a resilient portion of said blade adapted to snap said blade and Contact alternately to two extreme positions, and a rigid connection between the bimetallic member and the plate to effect said snap action upon movement of said member upon change in its temperature.

14. In a device of the kind described, a resilient switch blade, and a plate, said blade being pivotally supported on the plate, said blade including an interiorly disposed resilient tongue abutting an edge of said plate at its tree end and being under compression to maintain said blade on and in a plane at an angle to the plane oi.' the plate.

15. In a device of the kind described, a base, a thermally actuatable member ilxed to said base at one end, a plate pivoteci to said base, a resilient switch blade pivotally mounted on said plate, said blade including a resilient tongue under compression abutting by a free end an edge of the plate to maintain said blade and plate in pivotal relation and to maintain said blade in a plane at an angle to said plate at one side thereof or the other, a contact on said base, a stop mounted in spaced relation to said contact, an end of said blade being adapted to move between the contact and stop as limits, and a connection between the thermally actuatable member and the plate, whereby movement of said member upon change in temperature therein pivots said plate to eiect a snap movement of said blade from its then one position to its other position.

16. A circuit breaker comprising a base. a bracket thereon, a member pivoted to the bracket, said member having two edges parallel to its pivot axis and on opposite sides thereof, a groove in each edge, a switch blade including a cut away portion and an interiorly disposed resilient tongue, the distance between the end oi' the tongue and an opposed interior edge being less than the distance between the said grooves, said blade being pivotally supported by the said membei by means oi' the said interior edge and the edge oi the tongue resting within the said grooves, a contact on the blade remote from the pivotal support, a second contact, and means to pivot said member to eect a snap action between the member and the switch blade to snap make and break the contacts.

VICTOR WEBER. 20 

